Several patents and publications are cited in this description in order to more fully describe the state of the art to which this invention pertains. The entire disclosure of each of these patents and publications is incorporated by reference herein.
Jounce bumpers are found in vehicle suspension systems and typically comprise an elastic body mounted around a shock absorber rod and fixed to a structural element of the vehicle. The jounce bumper provides an elastic cushion for the end of travel of the shock absorber and coil spring under compression. The effect of the jounce bumper is to absorb impact, and it dampens noise, vibration and harshness (NVH) by preventing the articulated suspension components from fully compacting during shock impacts caused by heavy loads, potholes, curbs or objects in the road. In general, it is desired to maximize the absorption of energy in a jounce bumper in order to provide a progressive compression resistance and achieve a smoother ride over a wide range of driving and load conditions.
The energy absorption behavior of a jounce bumper can be measured by a compression test, where a plotted result of applied force and compression displacement (i.e. deformation) illustrates the elastic behavior of the jounce bumper. Usually deformation is plotted on the x-axis (in mm), and applied load (force) is plotted on the y-axis. Specifically, the area under the plotted curve represents the energy absorbed by the jounce bumper.
If the thickness profile of the wall of a jounce bumper is increased, the level of force required to compress the jounce bumper is also increased. However, this results in a stiffer jounce bumper but with reduced compression displacement, whereby less energy is absorbed in the jounce bumper.
An example of a jounce bumper with a non-uniform wall thickness is disclosed in US2014183804. Specifically, the wall thickness of the jounce bumper is non-uniform, such that the wall thickness in a root and a crest are different. The effect of the non-uniform wall thickness is a superior absorption of energy in relation to the applied force and axial deformation of the jounce bumper.